The present invention relates to electronic data storage and more specifically to a virtual electronic data library that supports mixed drive types using virtual libraries within a single library.
Existing data libraries typically employ a single drive type and one specific media format associated with the drive type. Generally, a data library is made up of a set of storage elements or slots housing tapes, disks or other media of a single type and format; one or more data input/output (I/O) elements of a single type and format, such as tape, disk or magneto-optical drives; and at least one transport for removing the media from the slots and inserting the media into the I/O elements. The transport generally takes the form of a robotic device that physically removes a medium from a slot, transports the medium to a drive element, and physically installs the medium in the drive. In larger libraries there may be more than one transport. Existing libraries generally have more than one tape drive, but all the drives and tapes are of the same type and format.
Generally, a controller card in the library system, such as may use a small computer systems interface (SCSI) standard, directs operations employing the different elements in the library. SCSI is an industry standard general-purpose parallel interface designed for providing high speed connections between one or more computers and one or more peripherals. Depending on the SCSI standard, a total of four, eight, or sixteen devices may be connected to one bus. A great advantage of SCSI is the ability to chain together multiple devices on a single physical I/O interface with each device having a unique address. SCSI is an interface system that is focused on a host adapter. The host adapter provides a shared bus that attached peripherals use to pass data to and from the host system. Theoretically, any SCSI device may be attached to any SCSI controller. The original SCSI standards supported four to eight devices on a single host adapter, but newer standards support high-speed operation of up to sixteen devices and bus lengths of up to twenty-five meters. Many SCSI devices have their own control circuitry. Such devices may carry out assigned tasks without direct control, freeing up the bus for other functions.
An existing method of extending the SCSI architecture employs a logical unit number (LUN) architecture. LUNs are assigned to SCSI devices deployed under the control of a primary SCSI device. Previously this has facilitated control of multiple devices, greater than the aforementioned limits, that are not connected directly to the SCSI bus. Thus, multiple devices under one SCSI device may be accessed through LUNs. However, since the SCSI bus has been widened from 8 to 16 devices, there has not been much need for such an extension. With overall performance targets in mind, the number of devices on the same SCSI bus has necessarily been minimized. Existing data libraries do not make use of LUNs.
Advances in drive and media technology have encouraged migration to different drive types for library uses. Since existing libraries employ only one drive type, such a migration in a existing data library system requires purchase of an entire new data library, or format conversion of the existing library. A media and/or drive upgrade may be desirable or necessary to accommodate higher density media, higher transfer rates, different media suppliers or be necessary due to a purchase of data, assets or an entire enterprise. Unfortunately, older media oftentimes will not function in newer drives. Additionally, to partition an existing library or to break a library into virtual libraries, special software has typically been required.
A virtual electronic data library system has a plurality of storage elements. Each of the storage elements is adapted to store a medium of a plurality of media. Preferably, a plurality of subsets of the media each have one format of a plurality of formats. A plurality of input/output elements are preferably adapted to receive and read the media stored in the storage elements. Each of the input/output elements is preferably capable of operatively receiving media having at least one of the formats. At least one transport is preferably adapted to remove the media from the storage elements and provide the media to the input/output elements. A library controller preferably has firmware wherein the subsets of the media are each assigned a logical unit number for use by the controller to partition the library. Preferably, at least one transport is operable to remove the media from the storage elements and operatively deploy the media for use by one of the input/output elements. The transport deploys the media to input/output elements according to the aforementioned logical unit numbers.
Another embodiment of an electronic data library system has a plurality of storage elements. Each of the storage elements is adapted to store a medium of a plurality of media having a plurality of formats, each of the formats having a logical unit number. At least one transport is operable to remove the media from the storage elements and operatively deploy the media for use by one of at least one input/output elements. At least one transport deploys the media in at least one input/output elements according to the logical unit number. A library controller directs at least one transport to deploy the media in at least one input/output elements according to the logical unit number.